Nonstationary Noise Estimator (nnse)

1. A method implemented by a noise estimation processor for estimating acoustic noise in an environment where a mobile communication device is operating and where the acoustic noise includes nonstationary noise or speech-like noises, and wherein the environment also includes speech signals, comprising: calculating, with the noise estimation processor, a composite frame energy signal from a current segment of an input signal, wherein the input signal comprises a frequency channel energy vector for a voice signal; searching, with the noise estimation processor, for a local minimum energy over a plurality of frames using at least two reference signals including a first signal comprised of a time-sensitive current local minimum energy estimate, emin, and a second signal comprised of a time-weighted average of previous detected local energy minima, eminmean; deciding, with the noise estimation processor, whether the detected local energy minima of the second reference signal is a noise signal; quantizing separately, with the noise estimation processor, an energy of each sub-band of the input signal; determining, with the noise estimation processor, a particular bin within a plurality of histogram bins that correspond to a quantized noise energy value for each sub-band such that detected input signal energy minima values are binned within the plurality of histograms; calculating, with the noise estimation processor, a composite noise energy estimate comprised of a weighted sum of a maximum probability noise energy estimate and an expected value noise energy estimate; and sending, by the noise estimation processor, the composite noise energy estimate to one or more of a noise suppressor configured to suppress noise based on the composite noise energy estimate, and a spectral shaper configured to enhance frequencies based on the noise energy estimate.

2. The method claimed in claim 1 , wherein searching, with the noise estimation processor, for the local minimum energy further comprises the step of: calculating, with the noise estimation processor, a difference signal, ediff, as a difference between the value of a last identified signal energy local minimum that is time-sensitive and the second signal comprised of a time-weighted average of previous detected local energy minima.

3. The method claimed in claim 2 , wherein the esum is not a new local minimum, a peak found flag, pk is set to zero and a “no peak found” counter, minpkcnt is incremented.

4. The method claimed in claim 2 , wherein searching, with the noise estimation processor, for the local minimum energy further comprises deciding, with the noise estimation processor, whether a current frame energy, esum, is a new local minimum energy.

5. The method claimed in claim 4 , wherein the esum is a new local minimum energy, the method updates the emin to equal esum.

6. The method claimed in claim 4 , further comprising using, with the noise estimation processor, a plurality of parameters and a reference signal that comprises variance of the eminmean signal, eminmeanVar, to detect the behavior of the input signal energy, wherein the parameters include ediff and minpkcnt.

7. The method claimed in claim 6 , wherein the parameter minpkcnt is compared to PKDWELL, wherein PKDWELL is a maximum allowed dwell time in which no local energy minima has been detected.

8. The method claimed in claim 6 , wherein the input energy signal is rising rapidly or decreasing slowly, or where no local energy minimum has been detected for a maximum allowed dwell time; and wherein ediff is less than zero, then emin is set equal to current frame energy, esum.

9. The method claimed in claim 6 , wherein the input energy signal is rising rapidly or decreasing slowly, or where no local energy minimum has been detected for a maximum allowed dwell time; wherein ediff is greater than zero, then emin is updated using an exponential smoothing function.

10. The method claimed in claim 6 , wherein the input energy signal is not rising rapidly or not decreasing slowly, or where local energy minimum has been detected within a maximum allowed dwell time; wherein ediff is less than zero emin is updated using an exponential smoothing function.

11. The method claimed in claim 6 , wherein ediff is greater than zero, emin is updated using an exponential smoothing function.

12. The method claimed in claim 1 , wherein searching, with the noise estimation processor, for the local minimum energy further comprises: generating, with the noise estimation processor, a first reference signal, emax, that tracks maximum peak energies of the input signal over a sequence of time frames; generating, with the noise estimation processor, a second reference signal, emaxmin, that tracks minimum of the first reference signal, emax; such that the range of the search is set by emaxmin; generating, with the noise estimation processor, a third reference signal, emin, that serves a reference in detecting local energy minima.

13. The method claimed in claim 1 , wherein calculating, with the noise estimation processor, the composite noise energy estimate further comprises: summing, with the noise estimation processor, a fractional multiple of the maximum probability noise energy estimate and a fractional multiple of the expected value noise energy estimate such that the sum of the fractional multipliers equal a value of one.

14. The method claimed in claim 1 , wherein the current segment of an input signal is represented as a vector of sub-band energies representing a frame of the input signal.

15. The method claimed in claim 1 , wherein the current segment of an input signal is represented as a full or partial sum of the sub-band energies representing a frame of the input signal.

16. The method claimed in claim 1 , wherein the current segment of an input signal is represented as a total energy calculated in a time domain representing a frame of the input signal.

17. The method claimed in claim 1 , further comprising supplementing, with the noise estimation processor, a noise estimator, for the mobile communication device, that is described by TIA-EIA-IS-127 industry standard.

18. The method claimed in claim 17 , wherein the supplemented noise estimator is combined with the nonstationary noise estimator (NNSE) when the NNSE determines a high probability of noise as a part of the input signal and when the supplemented noise estimator has erroneously not detected noise during a same instance of the input signal.

19. A non-transitory machine readable storage device, having stored thereon a computer program including a plurality of code sections comprising: code for calculating a composite frame energy signal from a current segment of an input signal; code for searching for a local minimum energy over a plurality of frames using at least two reference signals including a first signal comprised of a time-sensitive current local minimum energy estimate, emin, and a second signal comprised of a time-weighted average of previous detected local energy minima, eminmean; code for deciding whether the detected local energy minima of the second reference signal is a noise signal; code for separately quantizing an energy of each sub-band of the input signal; code for determining a particular bin within a plurality of histogram bins that correspond to a quantized noise energy value for each sub-band such that detected input signal energy minima values are binned within the plurality of histograms; and code for calculating a composite noise energy estimate comprised of a weighted sum of a maximum probability noise energy estimate and an expected value noise energy estimate.

20. The non-transitory machine readable storage device of claim 19 , wherein the code for searching for the local minimum energy further comprises: code for calculating, with the noise estimation processor, a difference signal, ediff, as a difference between the value of a last identified signal energy local minimum that is time-sensitive and the second signal comprised of a time-weighted average of previous detected local energy minima.

21. The non-transitory machine readable storage device of claim 19 , wherein the code for searching for the local minimum energy further comprises: code for generating, with the noise estimation processor, a first reference signal, emax, that tracks maximum peak energies of the input signal over a sequence of time frames; code for generating, with the noise estimation processor, a second reference signal, emaxmin, that tracks minimum of the first reference signal, emax; such that the range of the search is set by emaxmin; code for generating, with the noise estimation processor, a third reference signal, emin, that serves a reference in detecting local energy minima.

22. A communication device comprising: a microphone; and a noise estimation processor coupled to the microphone, the noise estimation processor adapted to: receive an input signal, the input signal comprising a frequency channel energy vector for a voice signal, calculate, a composite frame energy signal from a current segment of the input signal, search for a local minimum energy over a plurality of frames using at least two reference signals including a first signal comprised of a time-sensitive current local minimum energy estimate, emin, and a second signal comprised of a time-weighted average of previous detected local energy minima, eminmean, decide whether the detected local energy minima of the second reference signal is a noise signal, quantize separately an energy of each sub-band of the input signal; determine a particular bin within a plurality of histogram bins that correspond to a quantized noise energy value for each sub-band such that detected input signal energy minima values are binned within the plurality of histograms, calculate a composite noise energy estimate comprised of a weighted sum of a maximum probability noise energy estimate and an expected value noise energy estimate, and send the composite noise energy estimate to one or more of a noise suppressor and a spectral shaper.

23. The communication device of claim 22 , further comprising a transmitter coupled to the noise suppressor, the noise suppressor adapted to receive the composite noise energy estimate and the input signal, to suppress noise based on the composite noise energy estimate, and to produce a noise suppressed signal.

24. The communication device of claim 22 , further comprising a speaker, the speaker coupled to the spectral shaper, the spectral shaper adapted to receive the composite noise energy estimate and enhance frequencies of the based on the composite noise energy estimate, the signal envelope shaper to produce an enhanced signal.